Passive optical networks are becoming prevalent in part because service providers want to deliver high bandwidth communication capabilities to customers. Passive optical networks are a desirable choice for delivering high speed communication data because they may not employ active electronic devices, such as amplifiers and repeaters, between a central office and a subscriber termination. The absence of active electronic devices may decrease network complexity and/or cost and may increase network reliability.
FIG. 1 illustrates an exemplary passive optical network 100 adapted to provide fiber-to-the-premises (FTTP). As shown in FIG. 1, the optical network 100 may include a central office 110 that connects a number of end subscriber locations 115 (also called end user locations 115 herein) in a network. The central office 110 may additionally connect to a larger network, such as the Internet (not shown) or a public switched telephone network. The various lines of the network can be aerial or housed within underground conduits (e.g., see conduit 105).
In general, the optical network 100 includes feeder cables (e.g., main cable 120) associated at one end with the central office 110 and from which distribution cables branch. The main cable 120 may have on the order of 12 to 48 fibers; however, alternative implementations may include fewer or more fibers. The portion of network 100 that is closest to central office 110 is generally referred to as the F1 region, where F1 is the “feeder fiber” from the central office.
The optical network 100 may include fiber distribution hubs (FDHs) 130 that receive fibers of the feeder cable 120 extending from splice locations 125 and that output one or more distribution cables 122. In general, an FDH 130 is an equipment enclosure that may include a plurality of optical splitters (e.g., 1-to-8 splitters, 1-to-16 splitters, or 1-to-32 splitters) for splitting the incoming fibers of the feeder cable 120 into a number (e.g., 216 to 432) of output distribution fibers. The distribution cable 122 extends from an FDH 130 to a number of end user locations 115.
The optical network 100 typically includes breakout locations 116 at which branch cables (e.g., drop cables, stub cables, etc.) 124 are separated out from or electrically coupled (e.g., spliced, connectorized, etc.) to distribution cables 122. Breakout locations can also be referred to as tap locations, drop cable locations, splice locations, or branch locations. Branch cables can also be referred to as drop cables, drop lines, breakout cables, or stub cables.
Stub cables 124 are typically routed from breakout locations 116 to intermediate access locations 104 such as a pedestals, drop terminals, or hubs. Intermediate access locations 104 can provide connector interfaces located between breakout locations 116 and the end user locations 115. Drop cables are cables that typically form the last leg to an end user location 115. For example, drop cables can be routed from intermediate access locations 104 to end user locations 115. Drop cables also can be routed directly from breakout locations 116 to end user locations 115, thereby bypassing any intermediate access locations 104.
As noted above, the intermediate access locations 104 may be provided in the form of multi-service terminals such as drop terminals, optical termination enclosures, splice enclosure, etc. Optical termination enclosures are similar to multi-service terminals but are usually more re-enterable and may include splice trays and sealed ports for allowing pass-through cables to be routed through their housings such that the fibers can be accessed within the housings. Examples of multi-service termination are described in further detail in U.S. Pat. Nos. 7,397,997; 7,512,304; and 7,844,158, the entire disclosures of which are incorporated herein by reference. And, examples of optical termination enclosures are described in International Publication No. WO 2009/089327, the entire disclosure of which is incorporated herein by reference.
In certain embodiments, branch cables 124 can be coupled to distribution cables 122 using factory integrated terminations to provide environmentally sound and cost effective splicing protection. Factory integrated terminations may use factory integrated access (tap) points at specified points, such as at breakout locations 116, in the optical network 100 instead of manually installed splices. These factory integrated access points may be connectorized to provide a simple plug and play approach in the distribution portion of the optical network 100 when connecting end user locations 115 to the optical network 100. For example, implementations consistent with the principles of the disclosure may use rugged Outside Plant (OSP) connectors that can accommodate single or multi-port connectors. Examples of hardened or ruggedized fiber optic connectors, i.e., connectors that are adapted for outside environmental use and that may include environmental seals for preventing moisture/water intrusion, are described in International Publication No. WO 2009/076364, the entire disclosure of which is incorporated herein by reference.